Donald Trump’s personal Twitter account is the subject of a lawsuit filed on Tuesday by several users of the platform, including seven people whose accounts were blocked by the president after expressing their views in response to his posts.

The lawsuit argues (pdf) that by blocking users from viewing and replying to the account’s tweets, Mr. Trump and members of his communications team are violating the users’ First Amendment rights.

The group is represented by the Knight First Amendment Institute at Columbia University. Most of the plaintiffs, who include a sociology professor, a police officer and former Guantanamo Bay guard, and several writers, questioned or criticized Donald Trump and his policies by tweeting at his account before they were blocked. One, a writer named Joe Papp, was blocked a day after he responded to Trump’s withdrawal from the Paris Agreement on climate change and the president’s statement that he “was elected to represent Pittsburgh, not Paris.”

The Knight First Amendment Institute also joined the suit, arguing that even though it has not been blocked by @realDonaldTrump, the blocking of other users is a violation of its First Amendment right to hear from others in what should be considered a public forum.